Remove redundant default constructors when they're the only constructor (#8461)

* Initial plan

* Modernize C++ constructors to use C++11 default member initialization - Phase 1

Co-authored-by: nunoplopes <2998477+nunoplopes@users.noreply.github.com>

* Fix theory_pb.h struct definition - move reset() back inside struct

Co-authored-by: nunoplopes <2998477+nunoplopes@users.noreply.github.com>

* Modernize C++ constructors to use C++11 default member initialization - Phase 2

Co-authored-by: nunoplopes <2998477+nunoplopes@users.noreply.github.com>

* Fix opt_solver.h - revert rational initialization (complex type)

Co-authored-by: nunoplopes <2998477+nunoplopes@users.noreply.github.com>

* Modernize C++ constructors to use C++11 default member initialization - Phase 3

Co-authored-by: nunoplopes <2998477+nunoplopes@users.noreply.github.com>

* Fix sparse_matrix.h - explicitly initialize union member in default constructor

Co-authored-by: nunoplopes <2998477+nunoplopes@users.noreply.github.com>

* Remove unnecessary default constructors when they're the only constructor

Co-authored-by: nunoplopes <2998477+nunoplopes@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: nunoplopes <2998477+nunoplopes@users.noreply.github.com>

src/ast/ast.h

@@ -315,11 +315,11 @@ class sort_size {
         // of elements is at least bigger than 2^64.
         SS_FINITE_VERY_BIG,
         SS_INFINITE
-    } m_kind;
-    uint64_t m_size; // It is only meaningful if m_kind == SS_FINITE
+    } m_kind = SS_INFINITE;
+    uint64_t m_size = 0; // It is only meaningful if m_kind == SS_FINITE
     sort_size(kind_t k, uint64_t r):m_kind(k), m_size(r) {}
 public:
-    sort_size():m_kind(SS_INFINITE), m_size(0) {}
+    sort_size() = default;
     sort_size(uint64_t sz):m_kind(SS_FINITE), m_size(sz) {}
     explicit sort_size(rational const& r) {
         if (r.is_uint64()) {

src/ast/converters/converter.h

@@ -23,9 +23,9 @@ Notes:
 #include "ast/ast_translation.h"
 
 class converter {
-    unsigned m_ref_count;
+    unsigned m_ref_count = 0;
 public:
-    converter():m_ref_count(0) {}
+    converter() = default;
     virtual ~converter() = default;
 
     void inc_ref() { ++m_ref_count;  }

src/ast/expr_delta_pair.h

@@ -22,10 +22,10 @@ Revision History:
    \brief Auxiliary structure used to cache the intermediate results of the variable substitution procedure.
 */
 struct expr_delta_pair {
-    expr *    m_node;
-    unsigned  m_delta;
+    expr *    m_node = nullptr;
+    unsigned  m_delta = 0;
     
-    expr_delta_pair():m_node(nullptr), m_delta(0) {}
+    expr_delta_pair() = default;
     expr_delta_pair(expr * n, unsigned d):m_node(n), m_delta(d) {}
     unsigned hash() const { return hash_u_u(m_node->hash(), m_delta); }
     bool operator==(const expr_delta_pair & e) const { return m_node == e.m_node && m_delta == e.m_delta; }

src/ast/expr_stat.h

@@ -24,12 +24,11 @@ Revision History:
 class expr;
 
 struct expr_stat {
-    unsigned m_sym_count; // symbol count
-    unsigned m_depth;     // depth
-    unsigned m_const_count; // constant count
-    unsigned m_max_var_idx;  
-    bool     m_ground;
-    expr_stat():m_sym_count(0), m_depth(0), m_const_count(0), m_max_var_idx(0), m_ground(true) {}
+    unsigned m_sym_count = 0; // symbol count
+    unsigned m_depth = 0;     // depth
+    unsigned m_const_count = 0; // constant count
+    unsigned m_max_var_idx = 0;  
+    bool     m_ground = true;
 };
 
 /**

src/ast/substitution/expr_offset.h

@@ -26,10 +26,10 @@ Revision History:
 #include "ast/ast.h"
 
 class expr_offset {
-    expr *    m_expr;
-    unsigned  m_offset;
+    expr *    m_expr = nullptr;
+    unsigned  m_offset = 0;
 public:
-    expr_offset():m_expr(nullptr), m_offset(0) {}
+    expr_offset() = default;
     expr_offset(expr * e, unsigned o):m_expr(e), m_offset(o) {}
     
     expr * get_expr() const { return m_expr; }

src/ast/substitution/expr_offset_map.h

@@ -28,8 +28,7 @@ template<typename T>
 class expr_offset_map {
     struct data {
         T        m_data;
-        unsigned m_timestamp;
-        data():m_timestamp(0) {}
+        unsigned m_timestamp = 0;
     };
     vector<svector<data> > m_map;
     unsigned               m_timestamp;

src/ast/substitution/var_offset_map.h

@@ -29,8 +29,7 @@ class var_offset_map {
 protected:
     struct data {
         T        m_data;
-        unsigned m_timestamp;
-        data():m_timestamp(0) {}
+        unsigned m_timestamp = 0;
     };
     
     svector<data>           m_map;